Mirror galvanometers are used for example in laser scanners which deflection scan a laser beam, operating on the theory that when an electrical current is passed through a movable coil arranged in a magnetic field, an electromagnetic force is generated due to the interaction between the electrical current and the magnetic field, producing a rotational force (torque) proportional to the electrical current. The construction involves a device using galvanometer theory with a movable coil rotating to an angle where the torque and a spring force are in equilibrium, the presence or absence and size of a current being detected by an indicator needle swung by the movable coil. However instead of the indicator needle a reflecting mirror is provided on a member which rotates with the movable coil.
In practice mirror galvanometers use for example a movable piece of iron instead of the movable coil arranged in a magnetic field, with a magnetic path formed around the periphery of the movable piece of iron by means of a magnetic body involving two permanent magnets and four magnetic poles. The magnetic flux between the poles is altered by changing the size and direction of a current flowing in a drive coil wound around the magnetic body, so that a reflecting mirror is swung by the movable piece of iron, to thus deflection scan a laser beam (see for example "Practical Laser Technics", Kyoritsu Publishing Company, Dec. 20 1987, p210-212).
With the development of microelectronics represented by the high integration of semiconductor devices, there is now a range of equipment which is both highly functional as well as being miniaturized, and laser scanning systems and the like which use the abovementioned mirror galvanometer thus become applicable, as with laser adapted equipment such as laser microscopes. There is also a requirement for even further miniaturization.
With the conventional mirror galvanometer however, further miniaturization is difficult due for example to the movable coil being mechanically wound. Therefore, further miniaturization of laser scanning systems using such mirror galvanometers, and the laser adapted equipment using such laser scanning systems becomes difficult.
The present invention takes into consideration the above situation, with the object of providing for further miniaturization of laser scanning systems and laser adapted equipment using such laser scanning systems, by achieving miniaturization of the mirror galvanometer.